a)Aortic Stenosis
Types of Aortic Stenosis
Obstruction to left ventricular outflow is con~lnonly at the valvar level. Less commonly it is at the sub valvar or supra valvar level. Sub valvar obstruction
Even when aortic stenosis is critical, in the presence.of LV dysfunction, the gradient may be deceptively low. Similarly, some patients with severe aortic stenosis inay be asymptomatic.
Aortic stenosis patients usually present with angina, syncope or dyspnoen. In all symptomatic patients who do not have any serious co morbid conditions surgeiy is indicated. Even in those patients with severe LV dysfunction, operation should be performed, if they have anatomically severe stenosis. AVR in such cases results in haenlo dynamic improven~eilt and better functional status.Arneiican Herwt Association and American College of Cadiology have given guidelines for surgery and the class of evidence in their task force repoit
Surgical Techniques
Aortic Valvotomy
These days aortic valvotomy even in neonates and c itically ill infants is done under cardio pulinoilary bypass. Through a median stenlotomy, ascending aorta and right atrium are cannulated after heparinisation. On bypass aorta is clamped.Cold cardioplegia is administered into the aortic root. If necessary, retrograde cardioplegia is administered through coronary sinus. Transverse aortotomy is done.Aortic wall is retracted, valve inspected and itortic valvotoiny is done. The fused commissures are divided upto lrnm away from the junction of aorlic annulus.Division of unicomrnissural valve and of a rudimentary raphe will produce severe incompetence and so should be avoided, Occasionally myxornatous nodules could be removed without dainaging the cusps. Aortolomy is theii closed with continuous prolene sutures. It is good to monitor LA and PA pressures a1d measure aortic gradient and LV and RV pressures before closing Ihe chest.
Aortic Valve Replacement
The initial steps of the operation have been described earlier. Ascending aorta is cannulated. A single two-stage atrio-venous cannula is inserted through the right atrial appendage to IVC. Cardio plegia cannula is inserted into the ascending aorta and a retrograde cardiopiegia cannula into the coronary sinus. A left sided vent is inserted through the right superior pulmonary vein. Aorta is clamped at moderate hypothennia (28OC). If there is no aortic regurgitation,antegrade blood cardioplegi-a is given in the aortic root. Ice slush is applied in the pericardiurn to give additional myocardial protection. After heart is arrested,the rest of the cardioplegia is given retrograde. Hypertrophied ventricles need additional infusion of cardioplegia. If there is aortic regurgitation, the aorta is opened and direct antegrade cardioplegia is administered by cannulating the ostia with special hand held coronary arterial perfusion cannulae.
A transverse aortotomy 15 mrns above the origin of right coronary artery or an oblique one extending on to the non coronary sinus of aorta is made and stay sutures are taken. Lower aortotoiny flap is retracted and aortic valve is inspected. It is excised one cusp at a time leaving 2mm riin for suturing. When the valve is calcified, it has to be removed piece meal. A wet gauze piece is used to pack the inside of left ventricle to collect loose bits of calcium. Using a sharp knife, scissors or a bone rongeur calcium will have to be removed carefully taking precaution over the anterior mitral leaflet and the septum new the AV bundle (under the comrnissure between light and non coronary cusps).
The gauze piece from LV is removed. Aorta and LV are washed with saline that is sucked out. Wet peanut gauze is used to clean the areas from where calcium has been removed. Valve orifice is measured and appropriate 'sized valve is chosen.
Aortic Regurgitation
Types of Regurgitation
Aortic regurgitation can be acute or chronic.
Acute Aortic Regurgitation
The most dramatic presentation occurs in dissection of the aortic root.Endocarditis of the native or prosthetic aortic valve may also lead to acute regurgitation. The prosthetic valve which is stuck in open or semi open position could also present as acute aortic regurgitation. Iatrogenic cause of acute AR is after balloon valvotonly.
When a large regurgitant volume is suddenly imposed on a normal unprepared left ventricle, it leads to raised left ventricular end diastolic and left atrial pressures. Cardiac output falls and the only compensatory mechanism initially is tachycardia. This will be insufficient and patient presents 'with pulmonary oedema and cardiogenic shock. They require early surgery, as. &at is their only chance. Intra aortic balloon pump is contra indicate4 in the presence of aortic regurgitation.
Chronic Aortic Regurgitation
hi aetiological factors leading to aortic regurgitation are: (1) rheumatic,(2) annulo aortic ectasia, (3) native valve endocarditis, (4) congenital aortic valve disease, ( 5 ) floppy aortic valve with myxomatous degeneration. Prolapse of a cusp associated with VSD, (6) iatrogenic aortic valve problem, (7) syphilitic or atherosclerotic ascending aortic aneurysm, (8) aortitis in rheumatoid arthritis,
ankylosing spondylitis and Reiter's disease, (9) closed chest injury or spontaneous cusp rupture, and (10) Giant cell aoi-titis and
Takayasu's disease.
The asymptomatic phase is longer in aortic regurgitation when compared to aortic stenosis. The volume overload is compensated for a long period by compensatory hypertrophy to maintain normal ejection. The patients are asymptomatic in this compensated phase and left ventricular function is maintained. In the decompensated stage, the patients develop dyspnoea as left ventricular function becomes impaired. Left ventricular impairment is reversible in the early stages. Aortic valve replacement done at this stage will result in full recovery of left ventricular size and function. But if the ventricle develops progressive dilatation and reduced systolic function, irmnediate and late results of surgery become worse.
Indications for Surgery
Obstruction to left ventricular outflow is con~lnonly at the valvar level. Less commonly it is at the sub valvar or supra valvar level. Sub valvar obstruction
Even when aortic stenosis is critical, in the presence.of LV dysfunction, the gradient may be deceptively low. Similarly, some patients with severe aortic stenosis inay be asymptomatic.
Aortic stenosis patients usually present with angina, syncope or dyspnoen. In all symptomatic patients who do not have any serious co morbid conditions surgeiy is indicated. Even in those patients with severe LV dysfunction, operation should be performed, if they have anatomically severe stenosis. AVR in such cases results in haenlo dynamic improven~eilt and better functional status.Arneiican Herwt Association and American College of Cadiology have given guidelines for surgery and the class of evidence in their task force repoit
Surgical Techniques
Aortic Valvotomy
These days aortic valvotomy even in neonates and c itically ill infants is done under cardio pulinoilary bypass. Through a median stenlotomy, ascending aorta and right atrium are cannulated after heparinisation. On bypass aorta is clamped.Cold cardioplegia is administered into the aortic root. If necessary, retrograde cardioplegia is administered through coronary sinus. Transverse aortotomy is done.Aortic wall is retracted, valve inspected and itortic valvotoiny is done. The fused commissures are divided upto lrnm away from the junction of aorlic annulus.Division of unicomrnissural valve and of a rudimentary raphe will produce severe incompetence and so should be avoided, Occasionally myxornatous nodules could be removed without dainaging the cusps. Aortolomy is theii closed with continuous prolene sutures. It is good to monitor LA and PA pressures a1d measure aortic gradient and LV and RV pressures before closing Ihe chest.
Aortic Valve Replacement
The initial steps of the operation have been described earlier. Ascending aorta is cannulated. A single two-stage atrio-venous cannula is inserted through the right atrial appendage to IVC. Cardio plegia cannula is inserted into the ascending aorta and a retrograde cardiopiegia cannula into the coronary sinus. A left sided vent is inserted through the right superior pulmonary vein. Aorta is clamped at moderate hypothennia (28OC). If there is no aortic regurgitation,antegrade blood cardioplegi-a is given in the aortic root. Ice slush is applied in the pericardiurn to give additional myocardial protection. After heart is arrested,the rest of the cardioplegia is given retrograde. Hypertrophied ventricles need additional infusion of cardioplegia. If there is aortic regurgitation, the aorta is opened and direct antegrade cardioplegia is administered by cannulating the ostia with special hand held coronary arterial perfusion cannulae.
A transverse aortotomy 15 mrns above the origin of right coronary artery or an oblique one extending on to the non coronary sinus of aorta is made and stay sutures are taken. Lower aortotoiny flap is retracted and aortic valve is inspected. It is excised one cusp at a time leaving 2mm riin for suturing. When the valve is calcified, it has to be removed piece meal. A wet gauze piece is used to pack the inside of left ventricle to collect loose bits of calcium. Using a sharp knife, scissors or a bone rongeur calcium will have to be removed carefully taking precaution over the anterior mitral leaflet and the septum new the AV bundle (under the comrnissure between light and non coronary cusps).
The gauze piece from LV is removed. Aorta and LV are washed with saline that is sucked out. Wet peanut gauze is used to clean the areas from where calcium has been removed. Valve orifice is measured and appropriate 'sized valve is chosen.
Aortic Regurgitation
Types of Regurgitation
Aortic regurgitation can be acute or chronic.
Acute Aortic Regurgitation
The most dramatic presentation occurs in dissection of the aortic root.Endocarditis of the native or prosthetic aortic valve may also lead to acute regurgitation. The prosthetic valve which is stuck in open or semi open position could also present as acute aortic regurgitation. Iatrogenic cause of acute AR is after balloon valvotonly.
When a large regurgitant volume is suddenly imposed on a normal unprepared left ventricle, it leads to raised left ventricular end diastolic and left atrial pressures. Cardiac output falls and the only compensatory mechanism initially is tachycardia. This will be insufficient and patient presents 'with pulmonary oedema and cardiogenic shock. They require early surgery, as. &at is their only chance. Intra aortic balloon pump is contra indicate4 in the presence of aortic regurgitation.
Chronic Aortic Regurgitation
hi aetiological factors leading to aortic regurgitation are: (1) rheumatic,(2) annulo aortic ectasia, (3) native valve endocarditis, (4) congenital aortic valve disease, ( 5 ) floppy aortic valve with myxomatous degeneration. Prolapse of a cusp associated with VSD, (6) iatrogenic aortic valve problem, (7) syphilitic or atherosclerotic ascending aortic aneurysm, (8) aortitis in rheumatoid arthritis,
ankylosing spondylitis and Reiter's disease, (9) closed chest injury or spontaneous cusp rupture, and (10) Giant cell aoi-titis and
Takayasu's disease.
The asymptomatic phase is longer in aortic regurgitation when compared to aortic stenosis. The volume overload is compensated for a long period by compensatory hypertrophy to maintain normal ejection. The patients are asymptomatic in this compensated phase and left ventricular function is maintained. In the decompensated stage, the patients develop dyspnoea as left ventricular function becomes impaired. Left ventricular impairment is reversible in the early stages. Aortic valve replacement done at this stage will result in full recovery of left ventricular size and function. But if the ventricle develops progressive dilatation and reduced systolic function, irmnediate and late results of surgery become worse.
Indications for Surgery
Acute Aortic Regurgitation
Significant acute AR needs early surgical intervention.
Chronic Aortic Regurgitation
Several factors have to be taken into account before recommending surgery.These include severity of symptoms and LV function. With evidence of LV systolic dysfunction, even if the patient is asymptomatic or only with minimal symptoms, surgery is recommended. Waiting for more symptoms may lead to inevesible LV dysfunction.In patients with pure chronic AR; surgery should be considered only if AR is severe.
Aortic Valve Replacement
Aortic valve could be replaced with a prosthetic or bio prosthetic valve.
Technique: Surgical technique is not much different from what has already been described for aortic stenosis. Care must be taken to avoid VF soon after connecting the patient to cardio pulmonary bypass. Because of free aortic regurgitation, fibrillating heart will distend and produce myocardial damage. To avoid fibrillation, cooling is not started until the surgeon is ready to cross clamp the aorta, open it and administer cardioplegia.
The presence of aorlic regurgitation means that cardioplegia cannot be administered lo the aortic root. For antegrade cardioplegia, aorta has to be opened and by special hand held cannula it has to be administered. A hypertrophied and dilated heart will require excess amount of cardioplegic solution. For better protection retrograde coronary sinus cardioplegia is also given.
The combined aoi-tic valve stenosis and regurgitation may be of congenital or acquired aetiology, as in aortic stenosis. Most commonly in our country it is due to rheumatic heart disease. An episode of infective endocarditis on a previously stenotic valve may precipitate acute regurgitation.Many patients with severe aorlic stenosis may have mild regurgitation. Those with severe regurgitation may have mild aortic stenosis also. A few may have balanced lesions. Symptoms of one or the other may dominate. They have a particularly unfavorable outlook as" there is both pressure and volume overload on the ventricle.When indicated, the operation is valve replacement as valve repair procedures are usually unsuccessful.
Significant acute AR needs early surgical intervention.
Chronic Aortic Regurgitation
Several factors have to be taken into account before recommending surgery.These include severity of symptoms and LV function. With evidence of LV systolic dysfunction, even if the patient is asymptomatic or only with minimal symptoms, surgery is recommended. Waiting for more symptoms may lead to inevesible LV dysfunction.In patients with pure chronic AR; surgery should be considered only if AR is severe.
Aortic Valve Replacement
Aortic valve could be replaced with a prosthetic or bio prosthetic valve.
Technique: Surgical technique is not much different from what has already been described for aortic stenosis. Care must be taken to avoid VF soon after connecting the patient to cardio pulmonary bypass. Because of free aortic regurgitation, fibrillating heart will distend and produce myocardial damage. To avoid fibrillation, cooling is not started until the surgeon is ready to cross clamp the aorta, open it and administer cardioplegia.
The presence of aorlic regurgitation means that cardioplegia cannot be administered lo the aortic root. For antegrade cardioplegia, aorta has to be opened and by special hand held cannula it has to be administered. A hypertrophied and dilated heart will require excess amount of cardioplegic solution. For better protection retrograde coronary sinus cardioplegia is also given.
The combined aoi-tic valve stenosis and regurgitation may be of congenital or acquired aetiology, as in aortic stenosis. Most commonly in our country it is due to rheumatic heart disease. An episode of infective endocarditis on a previously stenotic valve may precipitate acute regurgitation.Many patients with severe aorlic stenosis may have mild regurgitation. Those with severe regurgitation may have mild aortic stenosis also. A few may have balanced lesions. Symptoms of one or the other may dominate. They have a particularly unfavorable outlook as" there is both pressure and volume overload on the ventricle.When indicated, the operation is valve replacement as valve repair procedures are usually unsuccessful.
No comments:
Post a Comment
Note: Only a member of this blog may post a comment.